If that is what I think it is, it looks like a gas chamber exercise. Everyone reacts to it differently, and it may have affected Jackson a lot harder than Bam Bam. I know they do it in American military basic training. This might be a similar exercise.

Some people get claustrophobic in chem gear. It can get really hot too. I know this first hand from being active duty US Air Force. Although it was hot in Nevada, it was at least dry. It was worse when I was stationed in Korea because it is so humid. Also some times in the training they have you start off without your masks on and you have to hurry and get it on after they set off smoke or tear gas. If you are too slow or the seal is not good, you inhale the stuff and it can gag you. In any case it is not a pleasant experience, but in the ROK it is necessary training because the North is lead by a very unstable leader who wouldn't hesitate to use chemical warfare.